Spinal fixation with selectively applied bone growth promoting agent

ABSTRACT

A spinal fixation system including a selectively applied bone growth promoting agent is disclosed. The types of spinal fixation systems which may include a selectively applied bone growth promoting agent include systems comprised of rods, plates, screws, and hooks as well as other types of prostheses.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to spinal fixation systems andin particular to spinal fixation systems including a selectively appliedbone growth promoting agent.

2. Description of Related Art

Spinal fusion implants have been previously proposed and utilized incervical thorastic, lumbar and sacral regions. Currently, these fixationsystems are utilized to hold various segments of the spine togetherallowing for fusion to occur. These implant systems include plates,screws, rods, hooks and cables utilized for the anterior, posterior aswell as lateral portions of the spine. All these systems utilize inertmaterials, mostly metal, to fix the bone and allow the natural processof healing to occur. None of these systems in use actually encourage thegrowth of bone to facilitate the fusion or healing. Furthermore, none ofthese systems utilize healing processes to heal to the actual implant byproviding a re-bar effect and better fixation.

One type of spinal fusion implant, the threaded spinal implant (commonlyreferred to as a spinal screw), may include provisions for promotingbone growth through the cage. This type of prosthesis is disclosed inMichelson (U.S. Pat. No. 6,264,656), the entirety of which isincorporated by reference. The threaded spinal implant is insertedbetween two adjacent vertebrae and is incorporated into the fusion ofthe bone along this portion of the spine.

Brantigan (U.S. Pat. No. 4,834,757) discloses plugs, used as spinalfusion implants, the entirety of which is incorporated by reference. Theplugs are rectangular with tapered front ends and tool receiving rearends. Generally, the plugs may be used in a similar manner to the spinalscrews of Michelson. As with the spinal screws, the plugs may beinserted between adjacent vertebrae. The plugs may include nubs thatbehave like teeth, countering any tendency for the plugs to slip betweenthe vertebrae.

While the related art teaches various forms of spinal fusion implants,there are many shortcomings. Related art prostheses lack selectivelyapplied bone growth promoting treatments. The prior art does not teachthe selective application of the variety of known bone growth promotingtreatments. There is therefore a need in the art for prostheses thatincorporate selectively applied bone growth promoting treatments.

SUMMARY OF THE INVENTION

A spinal fixation system including a bone growth promoting agent isdisclosed. In one aspect, the invention provides a spinal fixationsystem, comprising: a screw configured for implantation into at leastone vertebral body; the screw including a screw body; a rod that iscoupled to the screw using a coupling device, the rod including a firstregion and a second region; and where a bone growth promoting agent isselectively applied to the first region of the rod.

In another aspect, the rod is associated with two or more screws, eachscrew including a screw body with a bone growth promoting agentselectively applied to the screw body.

In another aspect, the coupling device includes a bone growth promotingagent.

In another aspect, the entire outer surface of the rod includes a bonegrowth promoting agent.

In another aspect, the rod is associated with multiple hooks andmultiple connecting devices for fixing the hooks to the rod, and whereinthe multiple hooks include a selectively applied bone growth promotingagent.

In another aspect, the invention provides a spinal fixation system,comprising: a first screw configured for implantation into a set ofcervical vertebrae and a second screw configured for implantation into afirst portion of the skull; the first screw and the second screw eachincluding a first screw body and a second screw body; a rod that iscoupled to the first screw and the second screw using a first couplingdevice and a second coupling device, the rod including a first regionand a second region; and where a bone growth promoting agent isselectively applied to the first region of the rod and the first andsecond screw bodies.

In another aspect, the first screw is associated with a first screw setthat is configured for implantation into the first portion of the skull.

In another aspect, the second screw is associated with a second screwset that is configured for implantation into the set of vertebrae withinthe spine.

In another aspect, the entirety of the rod includes a bone growthpromoting agent.

In another aspect, the screws comprising the first screw set includescrew bodies with a selectively applied bone growth promoting agent.

In another aspect, the screws comprising the second screw set includescrew bodies with a selectively applied bone growth promoting agent.

In another aspect, the first coupling device and the second couplingdevice include a bone growth promoting agent.

In another aspect, the invention provides a spinal fixation system,comprising: a plate associated with a set of vertebrae, including afirst side and a second side; the plate including at least one holeconfigured to receive at least one screw; and where a bone growthpromoting agent is selectively applied to the first side of the plate.

In another aspect, the bone growth promoting agent is selectivelyapplied to the entirety of the first side of the plate.

In another aspect, the first side includes a first region, and wherein abone growth promoting agent is selectively applied to the first region.

In another aspect, the plate is associated with an anterior side of theset of vertebrae.

In another aspect, the plate is associated with a lateral side of theset of vertebrae.

In another aspect, the plate is associated with a posterior side of theset of vertebrae.

In another aspect, the invention provides a spinal fixation system,comprising: a first plate associated with a vertebral lamina; a set ofscrews configured to attach the first plate to the vertebral lamina; andwhere a bone growth promoting agent is selectively applied to the firstplate.

In another aspect, the vertebral lamina is opened to widen a spinalcanal.

In another aspect, the vertebral lamina includes a first end and asecond end.

In another aspect, the first plate is associated with the first end andthe second end.

In another aspect, new bone growth associated with the plate fuses thespinal canal closed.

In another aspect, the invention provides a spinal fixation system,comprising: a screw including a first portion and a second portion; thefirst portion associated with a first vertebral body; the second portionassociated with a second vertebral body; and where a bone growthpromoting agent is selectively applied to the screw.

In another aspect, the screw is cannulated.

In another aspect, the first vertebral body is lumbar.

In another aspect, the second vertebral body is a sacrum.

In another aspect, the second vertebral body is also lumbar.

In another aspect, the invention includes a cable including a firstportion and a second portion; the first portion having a bone growthpromoting agent selectively applied in a first pattern; the secondportion having bone growth promoting agent selectively applied in asecond pattern; where the first pattern is different than the secondpattern.

In another aspect, the second pattern includes the bone growth promotingagent applied to the entire second portion.

In another aspect, the first pattern is substantially free of bonegrowth promoting agent.

In another aspect, the cable includes one or more strands of wire.

Other systems, methods, features and advantages of the invention willbe, or will become apparent to one with skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description, be within the scope ofthe invention, and be protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is an isometric view of a preferred embodiment of a rod;

FIG. 2 is a cross sectional view of a preferred embodiment of a rod;

FIG. 3 is a cross sectional view of a preferred embodiment of a rod;

FIG. 4 is a plan view of a preferred embodiment of a sheet material;

FIG. 5 is an isometric view of a preferred embodiment of a sheetmaterial being applied to a rod;

FIG. 6 is an isometric view of a preferred embodiment of a rod and asleeve;

FIG. 7 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent;

FIG. 8 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied along a single portion;

FIG. 9 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied along several portions;

FIG. 10 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied as a striped pattern;

FIG. 11 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied as a spotted pattern;

FIG. 12 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied as a geometric pattern;

FIG. 13 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied as a spiral pattern;

FIG. 14 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied as various patterns;

FIG. 15 is an isometric view of a preferred embodiment of a rod with abone growth promoting agent applied as various patterns;

FIG. 16 is an isometric view of a preferred embodiment of a rod with amodified surface texture;

FIG. 17 is a side view of a preferred embodiment of a microscopicsurface texture;

FIG. 18 is a side view of a preferred embodiment of a microscopicsurface texture;

FIG. 19 is a side view of a preferred embodiment of a microscopicsurface texture;

FIG. 20 is a top down view of a preferred embodiment of a threedimensional surface texture;

FIG. 21 is a top down view of a preferred embodiment of a threedimensional surface texture;

FIG. 22 is a top down view of a preferred embodiment of a threedimensional surface texture;

FIG. 23 is an isometric view of a preferred embodiment of a rod withvarious bone growth promoting agents;

FIG. 24 is an isometric view of a preferred embodiment of a solid rod;

FIG. 25 is an isometric view of a preferred embodiment of a hollow rod;

FIG. 26 is an isometric view of a preferred embodiment of a solid rodwith holes;

FIG. 27 is an isometric view of a preferred embodiment of a hollow rodwith holes;

FIG. 28 is a schematic cross sectional view of a preferred embodiment ofa hollow rod with holes;

FIG. 29 is a schematic cross sectional view of a preferred embodiment ofa rod inserted into bone;

FIG. 30 is a schematic cross sectional view of a preferred embodimentbone growing into a rod;

FIG. 31 is a cross sectional view of a preferred embodiment of animplantable prosthesis system;

FIG. 32 is an isometric view of a preferred embodiment of a fractureplate configured to attach to a bone;

FIG. 33 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 34 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 35 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 36 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 37 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 38 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 39 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 40 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 41 is an isometric view of a preferred embodiment of a fractureplate with a bone growth promoting agent;

FIG. 42 is an isometric view of a preferred embodiment of a linersystem;

FIG. 43 is a side cross sectional view of a preferred embodiment of afracture plate contacting a bone;

FIG. 44 is a side cross sectional view of a preferred embodiment of afracture plate with bony fusion;

FIG. 45 is a schematic cross section of a preferred embodiment of thethreading of a screw;

FIG. 46 is a schematic cross section of a preferred embodiment of thethreading of a screw;

FIG. 47 is a schematic cross section of a preferred embodiment of thethreading of a screw;

FIG. 48 is a schematic cross section of a preferred embodiment of thethreading of a screw;

FIG. 49 is a schematic cross section of a preferred embodiment of thethreading of a screw;

FIG. 50 is a schematic cross section of a preferred embodiment of thethreading of a screw;

FIG. 51 is a side view of a preferred embodiment of a screw;

FIG. 52 is a side view of a preferred embodiment of a screw;

FIG. 53 is a side view of a preferred embodiment of a screw;

FIG. 54 is a side view of a preferred embodiment of a screw;

FIG. 55 is a close up cross sectional view of a screw with a hollowboring tip;

FIG. 56 is a close up cross sectional view of a screw with a solidboring tip;

FIG. 57 is a schematic cross section of a preferred embodiment of ascrew inserted into bone;

FIG. 58 is a schematic cross section of a preferred embodiment of bonegrowing into a hollow central core of a screw;

FIG. 59 is a side view of a preferred embodiment of a spinal fixationsystem with selectively applied bone growth promoting agents;

FIG. 60 is a side view of a preferred embodiment of a spinal fixationsystem with selectively applied bone growth promoting agents;

FIG. 61 is a side view of a preferred embodiment of a spinal fixationsystem with selectively applied bone growth promoting agents;

FIG. 62 is a side view of a preferred embodiment of a spinal fixationsystem with bone growth;

FIG. 63 is a side view of a preferred embodiment of a spinal fixationsystem with selectively applied bone growth promoting agents;

FIG. 64 is a side view of a preferred embodiment of a spinal fixationsystem with selectively applied bone growth promoting agents;

FIG. 65 is a side view of a preferred embodiment of a spinal fixationsystem with bone growth;

FIG. 66 is a schematic view of a preferred embodiment of a plate withselectively applied bone growth promoting agents;

FIG. 67 is an isometric view of a preferred embodiment of a plate withselective regions including bone growth promoting agents;

FIG. 68 is a top view of a preferred embodiment of a plate withselectively applied bone growth promoting agents;

FIG. 69 is a top view of a preferred embodiment of a plate with bonegrowth;

FIG. 70 is a posterior view of a preferred embodiment of a plateassociated with the lateral side of two vertebral bodies;

FIG. 71 is a top down view of a preferred embodiment of a plateassociated with the lateral side of a vertebral body with bone growth

FIG. 72 is a posterior view of a preferred embodiment of one or morescrews associated with the lumbar spine; and

FIG. 73 is a posterior view of a preferred embodiment of one or morescrews with bone growth in the lumbar spine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a preferred embodiment of an implantable prosthesis in theform of rod 100. For clarity, the following detailed descriptiondiscusses a preferred embodiment, however, it should be kept in mindthat the present invention could also take the form of any other kind ofimplantable prosthesis including, for example, screws, fracture plates,cages, connectors, wires, cables, clamps, staples, anchors or any otherkind of prosthesis.

Often, an implantable prosthesis may include a provision for promotingbone growth. Generally, throughout this specification and the claims,such a provision will be referred to as a bone growth promoting agent.Bone growth promoting agents may be divided into two categories. Thefirst category includes any provision that uses additive components tothe prosthesis itself. The second category includes any provision thatmodifies the surface structure of the prosthesis, which is oftenmetallic.

The first category may include provisions that are freeze dried onto asurface or adhered to the metal through the use of linker molecules or abinder. Examples of the first category that may be applied through thesetechniques include, but are not limited to, bone morphogenetic proteins(BMPs), such as BMP-1, BMP-2, BMP-4, BMP-6, and BMP-7. These arehormones that convert stem cells into bone forming cells. Furtherexamples include recombinant human BMPs (rhBMPs), such as rhBMP-2,rhBMP-4, and rhBMP-7. Still further examples include platelet derivedgrowth factor (PDGF), fibroblast growth factor (FGF), collagen, BMPmimetic peptides, as well as RGD peptides. Generally, combinations ofthese chemicals may also be used. These chemicals can be applied using asponge, matrix or gel.

Some chemicals from the first category may also be applied to animplantable prosthesis through the use of a plasma spray orelectrochemical techniques. Examples of these chemicals include, but arenot limited to, hydroxyapatite, beta tri-calcium phosphate, calciumsulfate, calcium carbonate, as well as other chemicals.

Provisions from the second category generally modify the surfacestructure of the prosthesis. In some cases, the surface structure isroughened or provided with irregularities. Generally, this roughenedstructure may be accomplished through the use of acid etching, bead orgrit blasting, sputter coating with titanium, sintering beads oftitanium or cobalt chrome onto the implant surface, as well as othermethods. This can result in a prosthesis with a surface roughness withabout 3-5 microns of roughness peak to valley. However, in someembodiments, the surface roughness may be less than 3-5 microns peak tovalley, and in other embodiments, the surface roughness may be greaterthan 3-5 microns peak to valley. In some exemplary embodiments, theprosthesis can be made of commercially pure titanium or a titanium alloy(such as Ti6Al4V) with about 3-5 microns of roughness peak to valley.

It should be understood that the provisions listed here are not meant tobe an exhaustive list of possible bone growth promoting agents. The termbone growth promoting agent, as used in this specification and claims,is intended to include any method of modifying an implantable prosthesisthat stimulates bone growth either directly or indirectly.

Rod 100 preferably includes outer surface 102. In some embodiments,outer surface 102 preferably includes first portion 104 and secondportion 106. In this embodiment, coating 108 has been applied to secondportion 106 of outer surface 102. In a preferred embodiment, coating 108includes a bone growth promoting agent of some kind.

Referring to FIGS. 2-3, cross sections of first portion 104 and secondportion 106 preferably differ. In particular, second portion 106preferably includes coating 108. In this embodiment, coating 108preferably has some thickness. In other embodiments, the thickness ofcoating 108 may be varied.

As previously mentioned, bone growth promoting agents may be applied ina variety of ways. In some embodiments, bone growth promoting agents maybe applied to a mesh or fabric material that may be independentlymanufactured from the implantable prosthesis. In this manner, the fabricor mesh material, which includes the bone growth promoting agent, may beapplied to the implantable prosthesis at any time prior to surgery,during surgery or even after implantation. In addition to mesh or afabric material, the sheet can be any kind of bio-compatible materialthat includes a metallic foil, a plastic sheet or a biological matrix.The metal can be titanium, stainless steel, cobalt chrome or any othertype of bio-compatible metal or matrix.

Referring to FIGS. 4-5, sheet material 110 may be constructed to includea bone growth promoting agent. In some embodiments, sheet material 110may be any material that may be configured to include a bone growthpromoting agent, and that is flexible enough to wrap around animplantable prosthesis. In a preferred embodiment, sheet material 110may be a mesh or continuous fabric. In this embodiment, scissors 113 maybe used to cut sheet material 110 to a preconfigured size, which can beany desired size.

Once sheet material 110 has been cut to an appropriate size, it may beapplied to rod 100. Generally, sheet material 110 may be rolled over rod100. In some embodiments, sheet material 110 may be attached to rod 100through an adhesive. It is also possible to attach sheet material 110 torod 100 by using mechanical provisions, including hooks, microscopichooks, temperature difference, interference fit or a Morris taper. It isalso possible to attach sheet material 110 to rod 100 using magneticfeatures. In a preferred embodiment, sheet material 110 may bepreconfigured to include an adhesive for attaching to rod 100.

In some embodiments, a sheet material may be preconfigured as a sleeveor any desired shape. Preferably, the sleeve may be configured so that arod or another type of prosthesis may be inserted into the sleeve,without the need to wrap the sheet material around the prosthesis. Thesleeve can come in a variety of sizes and shapes. Like the sheetmaterial, the sleeve material may be constructed of a continuous or meshfabric, collagen, or biologic matrix, metallic foil or plastic sheet.

Referring to FIG. 6, sleeve material 112 may be constructed to include abone growth promoting agent. Preferably, sleeve material 112 may beconfigured to receive all or a portion of a rod 100. Generally, sleevematerial 112 may be configured to receive all or a portion of animplantable prosthesis. In this manner, a bone growth promoting agentmay be applied via sleeve material 112 by simply inserting theprosthesis into sleeve material 112. This configuration allows a bonegrowth promoting agent to be applied to a rod in an efficient manner.

Preferably, sheet material 110 and sleeve material 112 may be applied tomultiple types of implantable prosthesis, including, but not limited toscrews, fracture plates, cages, connectors, wires, cables, clamps,staples, anchors or any other kind of prosthesis. In some embodiments,sheet material 110 may be cut to a size configured to cover all or aportion of an implantable prosthesis. Additionally, sleeve material 112may be constructed in a manner that allows all or a portion of animplantable prosthesis to be inserted into sleeve material 112.

Preferably, a rod intended to be used as a prosthesis includesprovisions for selectively applying a bone growth promoting agent tovarious portions of the rod. In other words, a bone growth promotingagent need not be applied to the entirety of the rod. Instead, the bonegrowth promoting agent may be applied to a single portion of the rod. Insome embodiments, the bone growth promoting agent may be applied tomultiple, but not all, portions of the rod. Additionally, the bonegrowth promoting agent may be applied differently along differentportions of the rod. In this manner, the rod may be used todifferentially stimulate bone growth along various portions of theadjacent bone to simulate fusion, healing, stabilization and/orincorporation. This may be useful in cases where some, but not all,portions of the bone are damaged.

Referring to FIGS. 7-9, several embodiments of a rod may include a bonegrowth promoting agent that has been applied along various portions. Forthe purposes of illustration, the thicknesses of the portions includinga bone growth promoting agent have been exaggerated. Generally, thesethicknesses may vary. Some bone growth promoting agents may be appliedto the surface of a rod, or other prosthesis, and have no visiblethickness.

In some embodiments, the bone growth promoting agent may be applied tothe entirety of the rod. Rod 120 preferably includes bone growthpromoting agent 122 along the entirety of the length of rod 120. Bonegrowth promoting agent 122 may be any of the possible provisionsdiscussed previously for applying a bone growth promoting agent to animplantable prosthesis. With this configuration, rod 120 may help tostimulate bone growth along the entirety its length, following theimplantation of rod 120.

In other embodiments, a rod may include three portions, with only oneportion including a bone growth promoting agent. Rod 124 preferablyincludes first portion 126, second portion 128, and third portion 130.In a preferred embodiment, second portion 128 includes bone growthpromoting agent 132. With this configuration, rod 124 may help tostimulate bone growth along a portion of the bone adjacent to secondportion 128, following the implantation of rod 124.

In another embodiment, a rod may include four portions, with alternatingportions including a bone growth promoting agent. Preferably, rod 134may include first portion 136, second portion 138, third portion 140,and fourth portion 142. In some embodiments, only first portion 136 andthird portion 140 include bone growth promoting agent 144. With thisconfiguration, rod 134 may help to stimulate bone growth along portionsof the bone adjacent to first portion 136 and third portion 140,following the implantation of rod 134. In other embodiments, more orless than four portions may be provided.

In the previous embodiments, along portions where a bone growthpromoting agent has been applied, it has been preferably applieduniformly throughout the portion. In some embodiments, however, a bonegrowth promoting agent may be applied in particular patterns throughouta portion. Depending on the circumstances, different types of patternsmay be used to promote bone growth.

Examples of some patterns include stripes, spots, helical or spiral,geometric patterns, or combinations incorporating one or more of thesebasic pattern elements. The term geometric pattern refers to anypolygonal pattern including square (shown in the Figures), rectangular,polygon, honeycomb, repeating, non-repeating, regular, irregular, aswell as other types of patterns. A striped pattern includes thin linesof bone growth promoting agent that are disposed along a particularportion. In this arrangement, there is no bone growth promoting agentbetween the stripes. A spotted pattern may include small spots of thebone growth promoting agent. In a similar manner, a geometric patternmay include alternating shapes of a bone growth promoting agent. Variouspatterns may be used depending on the way in which the user wants toinduce bone growth along or adjacent to the prosthetic.

FIGS. 10-13 illustrate various patterns of bone growth promoting agentsapplied to rods. Rod 150 preferably includes first portion 152. In someembodiments, first portion 152 may include bone growth promoting agent154. In a preferred embodiment, bone growth promoting agent 154 may bedisposed in a striped pattern as shown in FIG. 10. This striped patternmay include one or more stripes. Generally, the thickness and/or densityof these stripes may be varied. Additionally, their orientation may alsobe varied. The shape, density and/or distribution of the bone growthpromoting agent will allow for selectively tailored bone growth orfusion.

In a second embodiment, rod 156 preferably includes first portion 158.In some embodiments, first portion 158 may include bone growth promotingagent 160. In a preferred embodiment, bone growth promoting agent 160may be disposed in spots along first portion 158. Generally, the shapeand/or density of these spots may be varied.

In a third embodiment, rod 162 preferably includes first portion 164. Insome embodiments, first portion 164 may include bone growth promotingagent 166. In a preferred embodiment, bone growth promoting agent 166may be disposed in a geometric pattern along first portion 164.Generally, the size of the squares comprising this geometric pattern maybe varied.

In a fourth embodiment, rod 170 preferably includes first portion 172.In some embodiments, first portion 172 may include bone growth promotingagent 174. In a preferred embodiment, bone growth promoting agent 174may be disposed in a spiral or helical pattern along first portion 172.Generally, the thickness and spacing of this spiral pattern may bevaried.

The patterns disclosed here are not intended to be exhaustive, but onlyillustrative of the various types of patterns that may be included inportions where a bone growth promoting agent is applied to a rod orother implantable prosthesis. Generally, any type of pattern may beused. Additionally, within the same portion, multiple patterns may besuperimposed.

Generally, various patterns of bone growth promoting agents may beselectively applied to multiple portions of a rod or other implantableprostheses. FIGS. 14-15 are a preferred embodiment of first rod 200 andsecond rod 202. In some embodiments, first rod 200 includes firstportion 204, second portion 206, and third portion 208. In someembodiments, a distinct pattern of a bone growth promoting agent may beselectively applied to each of the portions 204, 206, and 208. In apreferred embodiment, first portion 204 and third portion 208 mayinclude bone growth promoting agent 210 arranged as stripes. Likewise,second portion 206 may include bone growth promoting agent 212 arrangedas spots.

Preferably, second rod 202 includes first portion 216 and second portion218. In some embodiments, both first portion 216 and second portion 218include the same pattern of a bone growth promoting agent. In someembodiments, both portions 216 and 218 include a bone growth promotingagent arranged as stripes. In some embodiments, first portion 216includes first striped pattern 220 of a bone growth promoting agent,while second portion 218 includes second striped pattern 222 of a bonegrowth promoting agent. In a preferred embodiment, the density of firststriped pattern 220 is lower than the density of second striped pattern222. First striped pattern 220 can have different a orientation and canbe angled with respect to second striped pattern 222.

Referring to FIGS. 16-22, bone growth promoting agents may also beselectively applied to various portions of a rod by modification of thesurface properties. Preferably, rod 270 includes first portion 271. Insome embodiments, first portion 271 may include a bone growth promotingagent in the form of a textured surface. The structure of this surfacemay be seen in a close up of patch 272.

In some embodiments, first portion 271 may include a textured surfacedue to acid etching of titanium. In this case, a side view of patch 272,when viewed at the microscopic level, may include jagged peaks 274 andjagged valleys 273. In another embodiment, first portion 271 may includea textured surface due to grit blasting the titanium. In this case, aside view of patch 272, when viewed at a microscopic level, may includesharp peaks 276 and smooth valleys 275. Finally, in an embodiment whereplasma spraying is used to texture the surface of portion 271, a sideview of patch 272 may include rounded peaks 279, rounded valleys 278,and under surface 277.

Referring to FIGS. 20-22, some rods may be configured so that thesurface includes various three dimensional structures. In someembodiments, first surface 272 may include an irregular threedimensional surface. FIG. 20 shows an embodiment including an irregularporous titanium construct, including irregular structures 176 and firstpores 177. In a preferred embodiment, the sizes of first pores 177 maybe between 100 and 600 microns. In another embodiment, first surface 272may include a regular three dimensional surface. FIG. 21 shows anembodiment including a regular ball bearing type structure made oftitanium, including ball bearing-like structures 178 and second pores179. Second pores 179 may also have a size between 100 and 600 microns.In another embodiment, shown in FIG. 22, first surface 272 may include afibrous three dimensional surface. In this embodiment, the fibroussurface includes fibrous structures 180 and third pores 182. Using thesevarious types of three dimensional structures on the surface of rod 270allows for an increased surface area for new bone growth, as opposed totraditional surface treatment methods. In particular, the height orthickness of these various surface treatments may be large when comparedwith traditional surface treatments.

Other surface treatments that can be used include micro-porous coatings.Additionally, any and all coatings, treatments or patterns can be usedthat promote bone growth or allow for bone growth to the prosthesis andeffectively lock the prosthesis to the bone. In some embodiments, thesesurface treatments can provide the surface of the prosthesis with aroughness of about 3-5 microns, peak to valley, or a pore size of about1-850 microns as previously discussed. The pore size can be increased ifdesired. However, in other embodiments, the peak to valley roughnesswill be greater than 3-5 microns, and in other embodiments, the peak tovalley roughness may be less than 3-5 microns, depending on theapplication. In some cases, these surface treatments will be invisibleto the naked eye.

The specific surface treatment feature or combination of features can beselected based on: biology, location, bony region (metaphyseal orcortical bone; weight bearing or non-weight bearing, for example) cost,strength of the implant or prosthesis, geometry or size of the implantor prosthesis and manufacturing feasibility, among other criteria orfactors that may be considered.

In some embodiments, a rod may include a chemical bone growth promotingagent along one portion and a modified surface bone growth promotingagent along a second portion. In a preferred embodiment, shown in FIG.23, rod 282 may include first region 280 and second region 281. In someembodiments, each of the regions 280 and 281 may include a differentbone growth promoting agent. In a preferred embodiment, first region 280may include striped pattern 284 of a chemical bone growth promotingagent. Also, second region 281 may include acid etched surface 285,another type of bone growth promoting agent. For the purposes ofillustration, acid etched surface 285 is shown here with some shading,but generally, textured surfaces may be invisible to the naked eye.

Generally, some rods include provisions for modifying the structure ofthe rod. These modifications may include a hollowing out of the core ofthe rod. Additionally, these modifications may include the addition ofholes that may be disposed along the outer surface of the rod andpenetrate into the core of the rod.

Referring to FIGS. 24-27, rods may be configured solid, hollow, and withor without holes. If the rod includes holes, the holes can be anydesired size and shape. Also, the distribution pattern of the holes maybe varied. In one embodiment, a section of rod 230 may be solid. Rod 230may include outer surface 232. In a preferred embodiment, core 234 ofrod 230 may be solid. In a second embodiment, a section of rod 236 mayinclude hollow central core 238. Preferably, rod 236 includes outersurface 240. In a preferred embodiment, rod 236 may also include innersurface 242 of hollow central core 238.

Preferably, a third embodiment of a section of rod 244 may include holes246. Holes 246 are preferably disposed along the entirety of rod 244along outer surface 247. Holes 246 may also be disposed along a singleportion of rod 244 in other embodiments. Generally, holes 246 may be anydepth, any shape, angle, and have any size circumference. Similarly, thedensity of holes 246 may be varied in other embodiments. In someembodiments, a combination of holes having different sizes, shapes,angles or densities may be used.

A fourth embodiment of a section of rod 248 may preferably includehollow central core 250 as well as holes 252. Holes 252 are preferablydisposed along the entirety of rod 248. Generally, holes 252 may be anydepth, any shape, angle, and have any size circumference. Similarly, thedensity of holes 252 may be varied in other embodiments. In someembodiments, a combination of holes having different sizes, shapes,angles or densities may be used. Holes 252 may or may not penetratethrough to hollow central core 250. In a preferred embodiment, holes 252are disposed between outer surface 254 and inner surface 256 of hollowcentral core 250. In this manner, holes 252 preferably allow fluidcommunication between hollow central core 250 and outer surface 254,which allows bony ingrowth to occur into the interstices of rod 248.

Preferably, an implantable prosthesis system may include provisions forfusing the prosthesis to the bone. In some embodiments, a rod may beconfigured to be fused to a bone once it has been implanted. Inparticular, the rod may include provisions that allow the bone topenetrate through the outer surface and grow along an inner surface of ahollow core or into the holes themselves, and into the bone growthpromoting agent of the prosthesis.

In some embodiments, outer surface 254 may include bone growth promotingagent 258, seen in FIG. 28, a cross sectional view of rod 248. In someembodiments, inner surface 256 may also include bone growth promotingagent 258. Additionally, holes 252 may also be lined with bone growthpromoting agent 258. This configuration preferably allows bone to growalong outer surface 254 as well as inner surface 256, via holes 252.Bone growth can also occur into the holes themselves, and into the bonegrowth promoting agent of the prosthesis.

Referring to FIGS. 29-30, ingrowth of the bone from outer surface 254 toinner surface 256 may proceed once rod 248 has been inserted into asection of bone 290 or surrounded by bone 290, whether from a fractureor fusion. With time, portions 291 of bone 290 may grow through holes252 into hollow central core 289. In some embodiments, portions 291 mayfuse together inside hollow central core 289. In this way, rod 248 maybe fused with bone 290. In a preferred embodiment, holes 252 are used inconjunction with bone growth promoting agent 251 disposed along innersurface 256 and outer surface 254 in order to induce bone growth. Insome embodiments, bone growth promoting agent 251 may also be disposedwithin holes 252. In this manner, rod 248 may be partially or fullyintegrated into bone 290 as it heals.

Generally, in the rod embodiment disclosed above, or in any of theembodiments disclosed below, a combination of macroscopic holes andmicroscopic holes or other bone growth promoting surface treatments canbe used. By using a combination of both features, bone growth can beencouraged at the surface of the prosthesis so that the prosthesis, on asurface level, integrates with the bone; and by using macroscopic holes,large scale or bulk integration of the prosthesis can occur, furthersolidifying the integration of the prosthesis with the bone.

FIG. 28 is a cross sectional view of a preferred embodiment ofimplantable prosthesis system 296. Preferably, implantable prosthesissystem 296 is integrated into bone 292 (seen here in cross section).Preferably, implantable prosthesis system 296 may include rod 294, aswell as first bone screw 297 and second bond screw 298. In someembodiments, rod 294 may include bone growth promoting agent 299,disposed along a first portion 293 of rod 294. First portion 293 canrange from a relatively small portion of rod 294 to substantially all ofrod 294. In some embodiments, second screw 298 may also be coated withbone growth promoting agent 299. Generally, any desired number of screwsin system 296 can include bone growth promoting agents. It is alsopossible that the location of various, differently treated screws isvaried depending on the type of bone. For example, a screw for use incortical bone may have one type of bone growth promoting agent, while ascrew for use in cancellous or spongy bone has a second type of bonegrowth promoting agent. In this manner, the portion of bone 292 disposedadjacent to first portion 293 of rod 294 and second screw 298 may bestimulated to grow and fuse around rod 294 and second screw 298.

In an alternative embodiment, the implantable prosthesis may take theform of a fracture plate. In a manner similar to the rods discussed inthe previous embodiments, a bone growth promoting agent may be appliedto a fracture plate to stimulate bone growth. In a preferred embodiment,a bone growth promoting agent may be selectively applied to variousportions of a fracture plate, stimulating bone growth along variousportions of the bone.

FIG. 32 is an exploded isometric view of a preferred embodiment offracture plate 300 that may be attached to bone 302. Generally, fractureplate 300 may be attached to bone 302 using screw set 304. The screwscomprising screw set 304 may be inserted through screw hole set 306 offracture plate 300. With this arrangement, fracture plate 300 may beattached to bone 302 in order to add support to bone 302 while fracture308 heals. Generally, any number of screws and screw holes may be used.In this exemplary embodiment, there are eight screws comprising screwset 304 and eight screw holes comprising screw hole set 306.

In the preferred embodiments, the profile of fracture plate 300 isminimized by the long and narrow shape of fracture plate 300.Additionally, the profile may be minimized by the use of large screwholes. This reduction in profile may decrease the tendency of fractureplate 300 to interfere with the surrounding tissue and may also helpdecrease the weight of fracture plate 300 while maintaining a highdensity for strength and durability.

In the preferred embodiment, fracture plate 300 may also include smallholes 301 that are disposed on lower surface 310. Small holes 301 may bemacro and/or micro holes. Small holes 301 may extend partially intofracture plate 300, or may extend all the way through. Also, small holes301 may be disposed anywhere on lower surface 310, in any pattern,including a random pattern. The use of small holes 301 preferablyfacilitates both macro and micro fixation of bone growth.

In some embodiments, fracture plate 300 may include a lower surface 310.In some embodiments, lower surface 310 may be coated with bone growthpromoting agent 312. Preferably, in this embodiment, bone growthpromoting agent 312 may cover the entirety of lower surface 310.Generally, bone growth promoting agent 312 may be any of the types ofbone growth promoting agents discussed previously.

In some embodiments, an intermediate tissue or membrane is disposedbetween fracture plate 300 and bone 302. In other words, fracture plate300 may not directly contact bone 302. Instead, fracture plate 300 maybe configured to contact some other tissue or membrane disposed adjacentto bone 302. This membrane can include muscle or periosteum.

As with the rods in the previous embodiments, bone growth promotingagents may be selectively applied to various portions of fractureplates. In this way, different portions of a bone in contact with afracture plate may be stimulated to grow differently. Generally, a bonegrowth promoting agent may be applied to any portion of a fractureplate. Additionally, a bone growth promoting agent may be disposed inany pattern along the fracture plate. This may be useful in cases wheresome, but not all, portions of the bone are damaged.

Referring to FIGS. 32-41, bone growth promoting agents may be applied toa fracture plate in a variety of ways. The following embodiments areintended to illustrate possible configurations of fracture platesincluding one or more bone growth promoting agents, however it should beunderstood that these embodiments are only intended to be exemplary.Many other types of bone growth promoting agents, including variouspatterns may be applied to one or multiple portions of a fracture plate.Additionally, throughout the following embodiments, the bone growthpromoting agents may be used in combination with macro and micro holesin order to further facilitate bony fusion.

First plate 320 preferably includes first lower surface 321. In someembodiments, first lower surface 321 may include first portion 322 andsecond portion 324. In some embodiments, first portion 322 and secondportion 324 may have different treatments. In a preferred embodiment,first portion 322 is not treated. In a preferred embodiment, secondportion 324 may be treated with bone growth promoting agent 326.

As previously discussed, bone growth promoting agent 326 may includechemical treatments of the surface, or modifications to the texture ofthe surface of the prosthesis. Generally, the bone growth promotingagent applied to a fracture plate may be any type of bone growthpromoting agent discussed in the previous embodiments involving rods, aswell as any other bone growth promoting agent. In these embodiments, thebone growth promoting agents are visually distinct from the generalsurface to which they are applied. However, this is done purely forillustrative purposes. In some embodiments, the bone growth promotingagents may not be visible.

Second fracture plate 328 also preferably includes several portions. Insome embodiments, second plate 328 may include lower surface 329. Insome embodiments, second lower surface 329 may include first portion330, second portion 332, and third portion 334. In some embodiments,first portion 330 and third portion 334 may be treated in a similarmanner. In a preferred embodiment, first portion 330 and third portion334 both include bone growth promoting agent 336. In this manner, secondfracture plate 328 preferably helps to induce growth along portions ofthe bone adjacent to first portion 330 and third portion 334, but notsecond portion 332.

Additionally, fracture plates may be treated with a bone growthpromoting agent that is disposed along the outer surface in a variety ofdesigns. These designs may be similar to the designs discussed inprevious embodiments, or other types of designs. In some embodiments,fracture plates may include a bone growth promoting agent applied instriped, spotted, geometric patterns, and/or combinations of two or moreof these basic patterns.

Third fracture plate 338 preferably includes center portion 340 disposedalong lower surface 339. In some embodiments, center portion 340 mayinclude a bone growth promoting agent. In a preferred embodiment, centerportion 340 includes bone growth promoting agent 342 configured in astriped pattern.

In another embodiment, fourth fracture plate 344 also preferablyincludes center portion 346 disposed along lower surface 345. In someembodiments, center portion 346 may include a bone growth promotingagent. In a preferred embodiment, center portion 346 may include bonegrowth promoting agent 348 configured in a spotted pattern.

In another embodiment, fifth fracture plate 350 also preferably includescenter portion 352 disposed along lower surface 351. In someembodiments, center portion 352 may include a bone growth promotingagent. In a preferred embodiment, center portion 352 preferably includesbone growth promoting agent 354 configured in a geometric pattern.

In another embodiment, sixth fracture plate 356 may include threeseparate portions. Preferably, sixth fracture plate 356 includes firstportion 358, second portion 360, and third portion 362 disposed alonglower surface 357. In some embodiments, each portion may be treated witha different bone growth promoting agent. In some embodiments, firstportion 358 and third portion 362 may be treated with a similar patternof bone growth promoting agent. In a preferred embodiment, first portion358 and third portion 362 may include bone growth promoting agent 364configured in a striped pattern. Also, second portion 360 may preferablyinclude bone growth promoting agent 366 configured in a spotted pattern.

In some cases, different portions may be treated with the same patternof bone growth promoting agents, but the size or density of the patternmay differ between portions. Seventh fracture plate 368 preferablyincludes several portions disposed along lower surface 369. Inparticular, seventh fracture plate 368 preferably includes first portion370, second portion 372, and third portion 374. In some embodiments,each of these portions 370, 372 and 374 may include a bone growthpromoting agent disposed in a geometric pattern. In a preferredembodiment, first portion 370 and third portion 374 may include a firstbone growth promoting agent 376 disposed in a high density geometricpattern. Likewise, second portion 372 may include a second bone growthpromoting agent 378 disposed in a low density geometric pattern.

In the previous embodiments, a bone growth promoting agent was appliedalong portions that were disposed along the width of the fractureplates. In some embodiments, however, the bone growth promoting agentmay be disposed along portions that are oriented along the length of thefracture plates. Additionally, a fracture plate may be divided intoseveral portions disposed along the length of the fracture plate, eachportion including a different type of bone growth promoting agent.

FIG. 40 is a preferred embodiment of fracture plate 380. In someembodiments, fracture plate 380 may include lower surface 381. In someembodiments, lower surface 381 may be coated with bone growth promotingagent 382 along vertical portion 389. FIG. 41 illustrates an embodimentof a fracture plate. In this embodiment, fracture plate 315 includes adiagonally applied bone growth promoting agent 313 onto lower surface311. Using either a vertically or diagonally applied bone growthpromoting agent may facilitate new bone growth along the length of afracture plate.

In some embodiments, a fracture plate may include additional provisionsfor inducing bone growth, such as a porous surface. Additionally,fracture plate 380 may include holes 384 disposed along lower surface381. Generally, holes 384 may have circumferences of various sizes.Likewise, holes 384 may have various depths. Holes 384 need not bedisposed along the entirety of fracture plate 380. In some embodiments,holes 384 may be confined to one or multiple portions of a fractureplate. As disclosed above, fracture plate 380 is an example of aprosthesis that includes both macroscopic holes 384 and microscopic bonegrowth promoting features or agents 382. These macroscopic andmicroscopic features can be used in combination to help integratefracture plate 380 to the bone in a macroscopic and microscopic scale.

In another embodiment, a fracture plate may include a liner. In someembodiments, the liner may fit into a recess disposed in the fractureplate. However, in other embodiments, no recess is provided for theliner. Generally, the liner may be formed of or coated with a bonegrowth promoting agent. The bone growth promoting agent may be disposedon the liner in any pattern, such as those patterns described above withrespect to the fracture plate. In this manner, a liner with a bonegrowth promoting agent may be manufactured separately from the fractureplate, and combined with the fracture plate at the time of surgery,during implantation, or after implantation. It is also possible toprovide a fracture plate with a pre-installed liner so there is no needfor the surgeon to associate the liner with the fracture plate at thetime of surgery.

In some embodiments, the liner may be attached to the fracture platethrough an adhesive. It is also possible to attach the liner to thefracture plate by using mechanical provisions, including hooks,microscopic hooks, temperature difference, interference fit or a Morristaper. It is also possible to attach the liner to the fracture plateusing magnetic features. In some embodiments, liner may be preconfiguredto include an adhesive for attaching to the fracture plate.

FIG. 42 is an exploded view of a preferred embodiment of liner system400. Liner system 400 preferably includes fracture plate 402.Preferably, fracture plate 402 includes lower surface 422. In someembodiments, recess 420 may be disposed along lower surface 422 offracture plate 402. Recess 420 may include second set of holes 408.

Additionally, liner system 400 also preferably includes liner 404. Liner404 may be made of a similar material to fracture plate 402. In someembodiments, liner 404 may be a wafer of bone. Using a wafer of bone mayhelp facilitate bone to bone fusion. In some embodiments, liner 404 mayinclude lower surface 424. Preferably, lower surface 424 includes bonegrowth promoting agent 426. In a preferred embodiment, lower surface 424is disposed adjacent to bone 406. Liner 404 also preferably includesfirst set of holes 410.

In some embodiments, liner system 400 may also include mesh 425.Generally, mesh 425 may be treated with a bone growth promoting agent.In some embodiments, mesh 425 may be disposed between liner 404 and bone406. In other embodiments, liner system 400 may include only mesh 425 orliner 404. In some embodiments, mesh 425 may be a bone wafer, composite,bio-compatible material or a second liner.

In some embodiments, fracture plate 402 may be constructed of abio-absorbable material. In this manner, fracture plate 402 mayeventually dissolve into the tissue surrounding it. This is a preferredsituation over situations in which the fracture plate would need to beremoved via surgery. In a similar manner, the fracture plate 402, theliner 404 and/or the mesh 425 may be constructed of a bio-absorbablematerial. Liner 404 and/or mesh 425 can be constructed of bone, collagenor other biological or bio-compatible materials. In some cases, a bonewafer may be used. Additional liners and/or meshes may be used,resulting in more than two liners and possibly more than two meshes.

Generally, recess 420 may be configured to receive liner 404. In someembodiments, recess 420 has a depth that is equivalent to the thicknessof liner 404. In other embodiments, the thickness of liner 404 and thedepth of recess 420 may be varied.

Preferably, liner system 400 also includes screw set 412. In someembodiments, second set of holes 408 are configured to receive screw set412. Generally, first set of holes 410 and second set of holes 408 maybe aligned.

Once assembled, liner system 400 may be configured to add support tobone 406. In particular, as liner 404 preferably includes selectivelyapplied bone growth promoting agent 426 along lower surface 424, thismay help stimulate the growth of bone 406. Generally, a liner may alsoinclude various bone growth promoting agents that may be selectivelyapplied to various regions. The types of bone growth promoting agentsand the methods of selectively applying them may be substantiallysimilar to the previous embodiments.

In some embodiments, a fracture plate with holes may help induce bonegrowth that allows bone to grow into the holes. In this manner, the bonemay be partially fused to the fracture plate. Preferably, the plate mayinclude an additional bone growth promoting agent to help stimulate bonegrowth.

Referring to FIGS. 43-44, fracture plate 430 may preferably beconfigured to promote bone growth on the walls of first hole 434, secondhole 435, and lower surface 438. This may be achieved with or withoutthe use of a bone growth promoting agent. In a preferred embodiment,bone growth promoting agent 439 may be applied to holes 434 and 435.Generally, fracture plate 430 may be secured to bone 432 by some means,such as a screw. Over time, first portion 436 and second portion 437 ofbone 432 may grow into first hole 434 and second hole 435. In addition,bone growth will also occur into the surfaces of first hole 434 andsecond hole 435. In other words, bone growth can occur on a macroscopicscale—bone growth into holes 434 and 435—and on a microscopic scale aswell, bone growth onto the surfaces of holes 434 and 435 due to the bonegrowth promoting agent applied to the walls of holes 434 and 435.

In an alternative embodiment, the implantable prosthesis may take theform of a screw. In some cases, a screw may be configured to attachmultiple bones together. In other cases, a screw may be configured toattach a rod or a fracture plate to a fractured single bone. Generally,a screw may be used with many different kinds of implantable prostheses.

In a manner similar to the rods and fracture plates discussed in theprevious embodiments, a bone growth promoting agent may be selectivelyapplied to a screw to stimulate bone growth. Because a screw has asimilar structure to a rod, it follows that all of the variousmodifications that may be made to a rod to include selectively appliedbone growth promoting agents may also be applied to the screw disclosedhere. In particular, any of the bone growth agents previously disclosedmay be applied to any portion of a screw. Also, these bone growth agentsmay be applied in the patterns disclosed in the previous embodiments.

The term screw as used here applied to any device with threading. Insome cases, screws may or may not include a head. Screws can alsoinclude a solid or hollow boring tip. This solid boring tip allows thescrew to be inserted into a region of bone where no previous hole hasbeen made. Additionally, the head may be associated with a fasteningtool, such as a screw driver, hex key or a drill, allowing the screw tobe turned.

In FIG. 45, bone growth promoting agent 806 has been applied tothreading peaks 802 of threading 800 as well as threading valleys 804 ofthreading 800. This coating of the entirety of threading 800 may beaccomplished by dipping threading 800 in a chemical including bonegrowth promoting agent 806. The coating can also be applied by spraying,sintering, wax covering, as well as other suitable methods.

Additionally, it may be desirable in some cases to only coat a portionof the threading. This can provide different degrees of incorporationinto the bone. In some cases, limited degrees of incorporation may behelpful to assist in later removal of the screw. Referring to FIG. 46,it may be possible to only apply bone growth promoting agent 816 tothreading peaks 812 of threading 810. In this manner, threading valleys814 may not include bone growth promoting agent 816. This feature may beaccomplished by quickly dipping threading 810 into a chemical includingbone growth promoting agent 816 before the chemical has time to fillinto thread valleys 814. Additionally, the coating can also be appliedby spraying, sintering, wax covering, as well as other suitable methods.

In some cases, only the threading valleys may be coated. Referring toFIG. 47, threading valleys 824 of threading 820 may be coated with bonegrowth promoting agent 826. This may be accomplished by dippingthreading 820 into a chemical including bone growth promoting agent 826,and then spinning the screw in a manner that expels the bone growthpromoting agent 826 from threading peaks 822. Additionally, the coatingcan also be applied by spraying, sintering, wax covering, as well asother suitable methods.

In other embodiments, only portions of the threading may be coated.Referring to FIG. 48, threading 900 preferably includes upper portions904 and lower portions 902. In this embodiment, only upper portions 904of threading 900 may be coated with bone growth promoting agent 906.Likewise, in the embodiment shown in FIG. 49, threading 930 may includeupper portions 936 and lower portions 938. In this embodiment, onlylower portions 938 of threading 930 may be coated with bone growthpromoting agent 934. Finally, in the embodiment shown in FIG. 50, onlymiddle portions 922 of threading 920 may be coated with bone growthpromoting agent 924. As with the previous embodiments, each of thecoatings may be applied using techniques such as spraying, sintering,wax covering, as well as other suitable techniques.

In some embodiments, the structure of a screw may be modified. Suchmodifications include hollowing out the screw, as well as adding holesto the screw. Generally, a screw may be modified in ways similar to therods disclosed above. The screws may be fully, partially ornon-cannulated screws and the coatings may be applied in whole or inpart in a manner similar to the coatings applied to the rods asdisclosed above.

Referring to FIGS. 51-54, screws may be configured solid, hollow, andwith or without holes. One example of a hollow screw is a cannulatedscrew, which includes a hollow central shaft. In one embodiment, asection of screw 700 may be solid. Screw 700 also preferably includesscrew head 701 and boring tip 702. In some embodiments, bone growthpromoting agent 791 may be applied to first region 792. Preferably, bonegrowth promoting agent 791 is only applied to first region 792 and notthe entire shaft of screw 700. Likewise, throughout the remainingembodiments seen in FIGS. 52-54, bone growth promoting agents have beenapplied only to a selected region of the screw, not to the entirety. Inthis manner, screw 700 may stimulate bone growth along portions of abone disposed adjacent to first region 792.

In a second embodiment, screw 710 may include hollow central core 712.Second screw 710 may include screw head 703 and boring tip 704. In someembodiments, bone growth promoting agent 793 may be applied to firstregion 794. In this manner, screw 710 may stimulate bone growth alongportions of a bone disposed adjacent to first region 794.

Preferably, in a third embodiment, screw 720 may include holes 722.Holes 722 are preferably disposed along a first portion 713 of screw720. Generally, holes 722 may be any depth, any shape, angle, and haveany size circumference. Similarly, the density of holes 722 may bevaried in other embodiments. In some embodiments, a combination of holeshaving different sizes, shapes, angles or densities may be used.Preferably, screw 720 may also include screw head 705 and boring tip706. In some embodiments, bone growth promoting agent 795 may be appliedto second portion 796. In this manner, screw 720 may stimulate bonegrowth along portions of a bone disposed adjacent to first region 796.In a preferred embodiment, a bone growth promoting agent is not appliedto screw head 705.

A fourth embodiment of a section of screw 730 may preferably includehollow central core 732 as well as holes 736. Holes 736 are preferablydisposed along first portion 737 of screw 730. Generally, holes 736 maybe any depth, any shape, angle, and have any size circumference.Similarly, the density of holes 736 may be varied in other embodiments.In some embodiments, a combination of holes having different sizes,shapes, angles or densities may be used. In a preferred embodiment,holes 736 may be disposed between outer surface 729 and inner surface733 of hollow central core 732. In this manner, holes 736 preferablyallow fluid communication between hollow central core 732 and outersurface 729. Preferably, fourth screw 730 may also include screw head707 and boring tip 708. In some embodiments, bone growth promoting agent797 may be applied to first region 798. In this manner, screw 730 maystimulate bone growth along portions of a bone disposed adjacent tofirst region 798. In a preferred embodiment, inner surface 733 mayinclude bone growth promoting agent 782 as well. Bone growth promotingagent 782 applied to inner surface 733 may be similar or different thanbone growth promoting agent 797 that is applied to first region 798. Thevarious bone growth promoting agents can be selected to achievedifferent bone growth properties and/or to encourage different rates orkinds of bone growth. In a preferred embodiment, a bone growth promotingagent is not applied to screw head 707.

Generally, the length of the central cavities 712 and 732 of theprevious embodiments may be varied. Preferably, central cavities 712 and732 extend all the way to the bottom of screws 710 and 730. Instead, theend of screws 710 and 730 are preferably solid, as is preferable forboring into bone. Additionally, the tops of screws 710 and 730 need notbe configured open. In some embodiments, the tops of screws 710 and 730may be configured closed. Furthermore, screw heads in any embodiment mayinclude features to mate with any desired driver. For example, the screwheads may include a slot, Phillips, star, hexagonal cavity, torx,hexagonal nut or any other desired mechanical coupling. In otherembodiments, the screw does not have a head, and the shaft includesfeatures to mate with any desired driver.

Additionally, in some embodiments, the tips of the screws including bonegrowth promoting agents may be configured as open or closed. In otherwords, the tips may have a hollow or solid boring tip. Referring to FIG.55, a screw including tip portion 950 includes central cavity 952 thatextends all the way through boring tip 954. In another embodiment, seenin FIG. 56, a screw including tip portion 940 includes central cavity942 with a solid boring tip 944.

In a manner similar to the rods and cages of the previous embodiments, ascrew may be configured to promote ingrowth of bone and fuse with thebone. In some embodiments, a screw including holes and a hollow centralcore may be implanted into a bone. Once the screw has been implantedinside the bone, growth may occur through the holes into the hollowcentral core. In a preferred embodiment, the outer and inner surfaces ofthe screw may be coated with a bone growth promoting agent.

Referring to FIGS. 57-58, ingrowth of the bone from outer surface 836 toinner surface 832 may proceed once screw 830 has been inserted into asection of bone 834. With time, portions 840 of bone 834 may growthrough holes 838 into hollow central core 839. In some embodiments,portions 840 may fuse together within hollow central core 839. In thisway, screw 830 may be fused with bone 834. In a preferred embodiment,holes 838 are used in conjunction with bone growth promoting agent 899disposed along inner surface 832 and outer surface 836 in order toinduce bone growth. In some embodiments, bone growth promoting agent 899may also be disposed within holes 838. In this manner, screw 830 may bepartially or fully integrated into bone 834 as it is healing, micro andmacroscopically.

Generally, rods, screws and plates may be combined in a variety of waysto create spinal fixation systems. Typically, spinal fixation systemsare used to provide additional structural support to or betweenvertebrae. In some cases, spinal fixation systems may be associated withbone fusion between vertebrae. Spinal fixation systems may be associatedwith lumbar vertebrae, thoracic vertebrae as well as cervical vertebrae.In some embodiments, spinal fixation systems may be associated withcombinations of lumbar, thoracic and/or cervical vertebrae.Additionally, in some embodiments, spinal fixation systems may beassociated with the sacrum.

Preferably, each of these spinal fixation systems may be associated withregions of the spine where bone has been broken, fractured or damaged insome way. Therefore, it may be useful to consider the application ofselectively applied bone growth promoting agents to various portions ofthese fixation systems. Because some portions of spinal fixation systemsmay extend across regions of the spine that do not require new bonegrowth, it is an important feature of these spinal fixation systems thatthe bone growth promoting agents be selectively applied. By selectivelyapplying bone growth promoting agents, this may decrease or eliminatethe possibility that new bone growth will interfere with the intendedfunctionality of the system, as may occur in some cases where a bonegrowth promoting agent is applied to the entire device.

Throughout the remainder of this detailed description it should beunderstood that any rods disclosed are intended only as illustrativeembodiments of components of various spinal fixation systems. Aspreviously disclosed in this application, all rods may be configured assolid or hollow. Additionally, all screws may be configured as hollow orsolid. Finally, the terms rods, screws and plates refer to a generalcategory of objects. The terms rod, screw and plate are not meant toconfine the current disclosure to particular embodiments that includespecific geometries or various material constructions.

For clarity, the following embodiments discuss regions or portions ofspinal fixation systems with selectively applied bone growth promotingagents in a generic manner. It should be understood, however, that abone growth promoting agent may be selectively applied to each of thefollowing systems in a manner analogous to that discussed previously forrods. In particular, a bone growth promoting agent may be applied to arod, screw or a plate along any region, and in any pattern.Additionally, multiple different types of bone growth promoting agentsmay be used with rods, screws and/or plates, as well as other similardevices. Examples of these bone growth promoting agents and variouscoating patterns have been previously discussed.

Spinal fixation systems may include provisions for increasing bonyfusion. In some embodiments, one or more components of a spinal fixationsystem, including rods, plates, screws and coupling devices as well asother components, may include holes. In some cases, all of thecomponents of a spinal fixation system may include holes. In othercases, only some of the components of a spinal fixation system mayinclude holes. In still other embodiments, none of the components of aspinal fixation system may include holes.

In some embodiments, the number, size, shape and density of the holesmay vary. In some cases, a combination of macroscopic holes andmicroscopic holes or other bone growth promoting surface treatments canbe used. By using a combination of both features, bone growth can beencouraged at the surface of the spinal fusion device so that the spinalfusion device, on a surface level, integrates with the bone; and byusing macroscopic holes, large scale or bulk integration of the spinalfusion implant can occur, further solidifying the integration of thespinal fusion implant with the bone.

Furthermore, in some embodiments, the depth of each hole may vary. Insome cases, some or all of the holes may penetrate deep into a surfaceof a rod, plate, screw or other component of a spinal fixation system.In cases where a rod or screw has a hollow core, one or more holes maypenetrate through the surface of the spinal fusion device into a hollowcentral core of the rod, screw or other component of a spinal fixationsystem. In other embodiments, some or all of the holes may be shallowand only penetrate slightly into the surface of a rod, plate or screw.

In some embodiments, a selectively applied bone growth promoting agentmay be applied to one or more holes associated with a rod, screw, plateor other component of a spinal fixation system. In some cases, the bonegrowth promoting agent may be selectively applied to only some of theholes. In some cases, the bone growth promoting agent may be applied tothe bottom of a hole, the interior of the hole or some other portion ofthe hole.

It should be understood that any of the various configurations of holesdiscussed here, including combinations of these configurations, may beapplied to any component of a spinal fixation system discussed in thefollowing embodiments. Generally, any rod, plate or screw or othercomponent of a spinal fixation system discussed in the followingembodiments could include holes in some manner. In particular, bonegrowth promoting agents, as discussed above, may be selectively appliedto one or more holes associated with a rod, plate, screw or othercomponent of a spinal fixation system as discussed above.

FIGS. 59-62 illustrate a preferred embodiment of spinal fixation system1299 associated with lumbar vertebrae 1290. Lumbar vertebrae 1290preferably include multiple vertebral bodies, including first vertebralbody 1297 and second vertebral body 1298. In a preferred embodiment,first vertebral body 1297 is the L4 vertebral body and second vertebralbody 1298 is the L5 vertebral body. In some embodiments, spinal fixationsystem 1299 may also be associated with sacrum 1351.

In some embodiments, spinal fixation system 1299 may include rod 1300.Preferably, rod 1300 may be disposed along posterior side 1359 of lumbarvertebrae 1290. In this preferred embodiment, rod 1300 may extend fromfirst vertebral body 1297 to sacrum 1351. In other embodiments, rod 1300may extend to additional vertebrae beyond first vertebral body 1297.

Rod 1300 may have any desired geometry. In a preferred embodiment, rod1300 may be cylindrical. In other embodiments, the cross sectional shapeof rod 1300 may vary. Examples of cross sectional shapes for rod 1300include, but are not limited to rounded, oval, hexagonal, rectangular,as well as other cross sectional shapes. Additionally, rod 1300 may beconstructed to be solid, or to have a hollow core. Also, in someembodiments, rod 1300 may have macro and/or micro holes disposed alongouter surface 1291 (see FIG. 60). These possible variations of rod 1300should be understood to apply to any rod discussed throughout the restof this detailed discussion.

Preferably, spinal fixation system 1299 also includes first screw 1292,second screw 1293, and third screw 1294. First screw body 1304 of firstscrew 1292 is preferably inserted into first vertebral body 1297.Likewise, second screw body 1296 of second screw 1293 is preferablyinserted into second vertebral body 1298. In the preferred embodiment,third screw body 1307 of third screw 1294 may be inserted into sacrum1351. In this embodiment, screws 1292 and 1293 may be oriented at anglesclose to 90 degrees, with respect to rod 1300. Third screw 1294 ispreferably disposed at an obtuse angle with respect to rod 1300.

It should be understood that screws 1292-1294 could be any type of screwconfigured to insert into a vertebral body. Screws 1292-1294 may beconfigured as solid, hollow or cannulated. In other embodiments, screws1292-1294 could include macro holes to increase macro fixation of boneas well as micro holes to increase micro fixation of bone. Theseconfigurations may help to increase surface area for fusion as well ashelp to increase healing rates associated with spinal fixation system1299.

Although the preferred embodiment includes three screws associated withspinal fixation system 1299, in other embodiments, more or less thanthree screws may be used in conjunction with rod 1300. In someembodiments, for example, only two screws may be used. For example, inanother embodiment, spinal fixation system 1299 may include only firstscrew 1292 (associated with first vertebral body 1297) and second screw1293 (associated with second vertebral body 1298). In other embodiments,more than three screws may be used. Furthermore, the configurationdescribed here could be extended in scoliosis to include multiple levelsof screws, as well as plates and/or hooks.

Additionally, in some embodiments, spinal fixation system 1299 maycomprise a plate associated with multiple screws, rather than a rod withmultiple screws. Generally, any number of plates could be used inconjunction with screws to form a spinal fixation system associated withlumbar vertebrae 1290.

Generally, first screw 1292, second screw 1293 and third screw 1294 maybe attached to rod 1300 via first coupling device 1305, second couplingdevice 1295 and third coupling device 1306. First coupling device 1305,second coupling device 1295 and third coupling device 1306 may be anydevices that fix first screw 1292, second screw 1293 and third screw1294 in place with respect to rod 1300.

Generally, any type of screw to rod coupling system may be used. In someembodiments, a fixed coupling system may be used to keep the screwsfixed in place with respect to the rod. In other embodiments, a couplingdevice configured for a polyaxial screw may be used that allows thescrew some range of motion along different axes relative to the couplingdevice.

Preferably, spinal fixation system 1299 may include provisions forpromoting bone growth and/or bony fusion. In some embodiments, spinalfixation system 1299 may be associated with a bone growth promotingagent. In a preferred embodiment, each of the components comprisingspinal fixation system 1299 may include one or more bone growthpromoting agents.

Preferably, rod 1300 includes first region 1301 and second region 1302.In this embodiment, first region 1301 is disposed closer to lumbarvertebrae 1290 than second region 1302. In a preferred embodiment, firstregion 1301 may include selectively applied first bone growth promotingagent 1308. First region 1301 may be fully or partially coated withfirst bone growth promoting agent 1308. In some embodiments, multiplebone growth promoting agents may be applied to first region 1301. Itshould be understood that first region 1301 is only intended as anexample, and in other embodiment any region of rod 1300 could be coatedwith a bone growth promoting agent. In some embodiments, for example,the entirety of rod 1300 could include first bone growth promoting agent1308, as shown in FIG. 60.

In the preferred embodiment, shown in FIG. 59, screws 1292-1294 may alsoinclude a selectively applied bone growth promoting agent. Inparticular, screw bodies 1304, 1296 and 1307 may include a selectivelyapplied second bone growth promoting agent 1309. In some embodiments,second bone growth promoting agent 1309 may be applied to a singlescrew, or any combination of screws 1292-1294. Additionally, in otherembodiments, second bone growth promoting agent 1309 could be applied toonly the threading of screws 1292-1294 or only the surfaces of screws1292-1294 between the threading of screws 1292-1294, as previouslydiscussed.

Preferably, coupling devices 1305, 1295 and 1306 may also includeselectively applied third bone growth promoting agent 1319. In someembodiments, third bone growth promoting agent 1319 may be applied to asingle coupling device. In other embodiments, third bone growthpromoting agent 1319 may be applied to any combination of couplingdevices 1305, 1295 and 1306. In this preferred embodiment, third bonegrowth promoting agent 1319 may be applied to all three coupling devices1305, 1295 and 1306.

Using this configuration, spinal fixation system 1299 preferablyprovides rigid support to the damaged region of lumbar vertebrae 1290after surgical correction is performed. Additionally, first bone growthpromoting agent 1308 and second bone growth promoting agent 1309preferably help to stimulate bone growth along first region 1301 of rod1300 and screw bodies 1304, 1296, and 1307, which are all disposed closeto, or in contact with, lumbar vertebrae 1290. This preferably allowsbone to heal to fixation devices, or to form in these regions.

In some embodiments, the anatomy of the spine may not allow for the useof screws. In some cases, hooks may be used instead of screws. In theembodiment shown in FIG. 61, spinal fixation system 1310 preferablyincludes first hook 1311, second hook 1312, third hook 1313, and fourthhook 1314. First hook 1311, second hook 1312, third hook 1313 and fourthhook 1314 preferably attach to lumbar vertebrae 1290 at lamina 1321. Inthis embodiment, hooks 1311-1314 may be attached to rod 1300 by couplingmechanisms similar to those disclosed in the previous embodiments.Generally, the types of coupling mechanisms used may vary. Additionally,as with the previous embodiment, the number of hooks used with spinalfixation system 1310 may vary.

Preferably, hooks 1311-1314 include provisions for fusing directly tolamina 1321 of lumbar vertebrae 1290. In some embodiments, bone growthpromoting agent 1315 may be selectively applied to portions of hooks1311-1314. With this preferred configuration, bone growth promotingagent 1315 preferably facilitates bone growth along the spine. This newbone growth may eventually lead to fusion between spinal fixation system1310 and lumbar vertebrae 1290.

Referring to FIG. 62, new bone growth of a preferred embodiment ofspinal fixation system 1299 may be observed. The current embodimentrefers to bone growth for a spinal fixation system including rods andscrews, however a similar type of bone growth may occur with a spinalfixation system incorporating plates and/or hooks. In this embodiment,first new bone growth 1322 may be observed along first screw 1292,second screw 1293 and third screw 1294 where second bone growthpromoting agent 1309 has been previously applied. Additionally, secondnew bone growth 1323 may be observed along first region 1301 of rod 1300where first bone growth promoting agent 1308 has been previouslyapplied. With this arrangement, spinal fixation system 1299 may bepartially fused to, and/or incorporated with, lumbar vertebrae 1290.This arrangement is preferred to prior designs where spinal fixationsystems do not facilitate new bone growth, or are not configured topromote bony fusion only at particular portions of the spinal fixationsystem.

This preferred arrangement preferably creates a rebar effect,reinforcing the strength of the connection between adjacent vertebrae.This arrangement also helps to incorporate the various components ofspinal fixation system 1299 into the bone or bones. This design isadvantageous over previous technologies that only allow for fixation ofadjacent vertebrae using a fixation system, but not the incorporation ofone or more components of the fixation system into the bone to augmentfusion or healing.

Generally, spinal fixation systems using screws or hooks may beassociated with a particular side of the spine. In the previousembodiments, for purposes of clarity, the spinal fixation systems wereassociated with the left half of posterior side 1359 of lumbar vertebrae1290. In other embodiments, the spinal fixation systems may beassociated with the right side of the spine. In some cases, a surgeonmay decide to use a pair of spinal fixation systems. Therefore, in someembodiments, a second spinal fixation system, substantially similar tothe first in all respects, may be associated with the right half ofposterior side 1359 of lumbar vertebrae 1290. Throughout the remainderof this disclosure, all fixation systems are shown as a single fixationsystem disposed on a particular side of the spine. It should be kept inmind, however, that each of these fixation systems could also be placedalong the opposite side of the spine and in many cases a pair offixation systems could be used along both the right and left sides ofthe spine, especially on the posterior side of the spine.

Also, while the previous embodiments included spinal fixation systemsassociated with the posterior side of lumbar vertebrae 1290, in otherembodiments, spinal fixation systems may be associated with other sidesof lumbar vertebrae 1290. In some embodiments, a spinal fixation systemsimilar to the embodiments shown here, including a selectively appliedbone growth promoting agent, may be associated with a lateral side oflumbar vertebrae 1290. In other embodiments, a spinal fixation systemsimilar to the embodiments shown here, including a selectively appliedbone growth promoting agent, may be associated with an anterior side oflumbar vertebrae 1290. Finally, spinal fixation system 1299, includingthe variations discussed in this detailed description, could also beconfigured to attach to both thoracic and cervical vertebrae in someembodiments.

In another embodiment, a spinal fixation system may be applied to thecervical area of the spine. The spinal fixation system may include a rodas well as screws. In a preferred embodiment, one or more bone growthpromoting agents may be applied to a portion of the spinal fixationsystem.

The following preferred embodiment of a spinal fixation system uses arod and screws. However, it should be understood that in otherembodiments, a plate could also be used. In some cases, a plate could beused instead of a rod. In other cases, plates and rods may both be usedwith screws in a spinal fixation system.

FIGS. 63-65 are a preferred embodiment of spinal fixation system 1329.In the current embodiment, spinal fixation system 1329 is a cervicalfixation system. Spinal fixation system 1329 may be associated withfirst portion 1356 of skull 1357. In some embodiments, first portion1356 is the occipital bone. Spinal fixation system 1329 is alsopreferably associated with cervical vertebrae 1354.

In this embodiment, spinal fixation system 1329 preferably includes rod1331. Generally, rod 1331 may extend from first portion 1356 of skull1357 to lower portion 1342 of cervical vertebrae 1354. In some cases,rod 1331 may extend below lower portion 1342 of cervical vertebrae 1354.In other embodiments, rod 1331 may only extend to an intermediateportion of cervical vertebrae 1354. However, in other embodiments, rod1331 may extend to thoracic vertebra 1398 and, in some cases, additionalthoracic vertebrae as well.

Preferably, rod 1331 may be associated with various screws that fix rod1331 into place along cervical vertebrae 1354. In this embodiment, rod1331 may be associated with first screw set 1334 and second screw set1353. Each screw of first screw set 1334 and second screw set 1353 maybe fixed to rod 1331 through first coupling mechanism set 1336 andsecond coupling mechanism set 1337, respectively. Examples of suchcoupling mechanisms have been described in prior embodiments. For thepurposes of the current embodiment, any type of coupling device could beused.

First screw set 1334 may be associated with cervical vertebrae 1354. Insome embodiments, the screws comprising first screw set 1334 may beinserted into the lateral mass of cervical vertebrae 1354 or thepedicles of cervical vertebrae 1354. Second screw set 1353 may beinserted into first portion 1356 of skull 1357. Generally, the number ofscrews in each screw set, 1334 and 1353, may vary. In this embodiment,both first screw set 1334 includes six screws and second screw set 1353includes four screws.

Preferably, spinal fixation system 1329 includes provisions forfacilitating new bone growth. In some embodiments, rod 1331 may includefirst portion 1332 and second portion 1333. Preferably, first portion1332 is disposed closer to cervical vertebrae 1354 than second portion1333. In this embodiment, first portion 1332 includes selectivelyapplied first bone growth promoting agent 1340. In other embodiments,first bone growth promoting agent 1340 may be applied to the entirety ofrod 1331, as seen in FIG. 64. In an alternative embodiment including aplate instead of a rod, a bone growth promoting agent may be selectivelyapplied to the plate as well.

Referring to FIG. 63, in some embodiments, first screw set 1334 andsecond screw set 1353 may also include a bone growth promoting agent.Preferably, screws comprising first screw set 1334 and second screw set1353 include screw bodies 1335. Screw bodies 1335 are preferablythreaded, and anchor rod 1331 into place as it is inserted into cervicalvertebrae 1354. In a preferred embodiment, second bone growth promotingagent 1341 may be selectively applied along screw bodies 1335. In otherembodiments, only portions of screw bodies 1335 (including either thethreading or the intermediate surfaces between the threading) may beassociated with second bone growth promoting agent 1341.

In some embodiments, the use of cables associated with spinal fixationsystem 1329, or independently of spinal fixation system 1329, may helpincrease the rate of healing. Referring to FIGS. 63-65, in someembodiments cables 1317 may be associated with spinous processes 1369 orlamina of cervical vertebrae 1354. Cables 1317 may be inserted throughsmall holes 1330 of adjacent spinous processes comprising spinousprocesses 1369 that have been drilled into spinous processes 1369 ormade using another method. In other embodiments, cables 1317 may belooped around lamina or spinous processes of cervical, thoracic orlumbar bodies to provide fixation and augment fusion. Cables 1317 arepreferably tied in loops to hold adjacent vertebrae of cervicalvertebrae 1354 together during healing. In a preferred embodiment,cables 1317 may include bone growth promoting agent 1399, which mayfacilitate the fusing of cables 1317 to spinous processes 1369. Thispreferred arrangement may facilitate increased healing rates by allowingadditional bone growth between adjacent vertebrae.

Spinal fixation system 1329 preferably provides rigid support to thespine after surgical correction is performed. Using one or more bonegrowth promoting agents along spinal fixation system 1329 preferablyfacilitates new bone growth. Specifically, in this embodiment, new bonegrowth is preferably accomplished along screw bodies 1335 and firstportion 1332 of rod 1331. Referring to FIG. 65, first new bone growth1352 can be observed along first portion 1332 of rod 1331. Likewise,second new bone growth 1358 can be observed along screw bodies 1335 offirst screw set 1334 and second screw set 1353 and on cables 1317. Withthis configuration, spinal fixation system 1329 may be fused withcervical vertebrae 1354, thoracic vertebrae 1398 and skull 1356 (seeFIG. 63), allowing for continuous structural support.

This preferred arrangement preferably creates a rebar effect,reinforcing the strength of the connection between adjacent vertebrae.This arrangement also helps to incorporate the various components ofspinal fixation system 1329 into the bone or bones. This design isadvantageous over previous technologies that only allow for fixation ofadjacent vertebrae using a fixation system, but not the incorporation ofone or more components of the fixation system into the bone to augmentfusion or healing.

As with the rods in the previous embodiments, bone growth promotingagents may be applied to plates used with spinal fixation systems. Thesebone growth promoting agents may be applied to the entire surface of theplate or may be selectively applied to various regions of the platesurface. With this arrangement, different portions of a bone in contactwith a plate may be stimulated to grow differently.

Generally, a bone growth promoting agent may be applied to any portionof a plate. Additionally, a bone growth promoting agent may be disposedin any pattern along a plate. Examples of bone growth promoting agentsand patterns that may be associated with plates have been previouslydiscussed. The use of plates with selectively applied bone growthpromoting agents may be useful, for example, to promote new bone fusionacross an interbody space or where only some parts of a vertebral bodyare damaged and require new bone stimulation.

Referring to FIGS. 66-67, spinal fixation system 1345 may be associatedwith anterior side 1318 of vertebrae 1360. Vertebrae 1360 may be anytype of vertebrae, including lumbar vertebrae, thoracic vertebrae and/orcervical vertebrae. In some embodiments, vertebrae 1360 may includevertebrae of more than one type. In this preferred embodiment, vertebrae1360 preferably comprise first vertebral body 1421, second vertebralbody 1422, third vertebral body 1423, fourth vertebral body 1424 andfifth vertebral body 1425. Additionally, vertebrae 1360 may beassociated with first interbody space 1431, second interbody space 1432,third interbody space 1433 and fourth interbody space 1434. Theseinterbody spaces 1431-1434 are generally associated with discs.

In some embodiments, spinal fixation system 1345 may comprise plate1361. Plate 1361 may have any shape, including any length, width orthickness. In this preferred embodiment, plate 1361 has a lengthconfigured so that it spans three vertebrae 1422-1424 and interbodyspaces 1432 and 1433.

Preferably, plate 1361 includes first hole set 1441, second hole set1442 and third hole set 1443, associated with second vertebral body1422, third vertebral body 1423 and fourth vertebral body 1424,respectively. Generally, sets of holes 1441-1443 may be configured toreceive screws 1364. Screws 1364 may be inserted into vertebral bodes1422-1424. This preferred arrangement allows plate 1361 to fix vertebralbodes 1422-1424 in place with respect to one another.

In some embodiments, the number of holes comprising sets of holes1441-1443 and the number of screws comprising screws 1364 may vary. Inthis preferred embodiment, there are six holes and six screws. Inanother embodiment, for example, there may only be four holes and fourscrews. This alternate configuration may be used when only two vertebraeare being fused, rather than three vertebrae as with the currentembodiment.

In this embodiment, plate 1361 includes first surface 1362. Generally,first surface 1362 may be disposed adjacent to vertebrae 1360. In apreferred embodiment, first surface 1362 may be configured to contactvertebrae 1360. In some embodiments, first surface 1362 may includeregion 1368. Preferably, region 1368 includes bone growth promotingagent 1367.

As screws 1364 are inserted through sets of holes 1441-1443 and intovertebral bodies 1422-1424, plate 1361 may be fixed against vertebrae1360. Using this configuration, bone growth promoting agent 1367,disposed along region 1368 preferably facilitates bone growth alongvertebrae 1360. By selectively applying bone growth promoting agent 1367to region 1368, new bone growth may be facilitated between vertebralbodies 1422-1424, and within interbody spaces 1432-1433, eventuallyfusing vertebral bodies 1422-1424 together to provide maximum support.

Referring to FIG. 67, in some embodiments, plate 1361 may include firstwide hole 1371 and second wide hole 1373. Wide holes 1371 and 1373 arepreferably associated with region 1368, where new bone growth isexpected to take place. Because plate 1361 is often comprised of metal,it may be difficult for a surgeon to observe new bone growth with anx-ray under plate 1361. Therefore, wide holes 1371 and 1373 provide thesurgeon with an easy way to observe new bone growth along region 1368,or between vertebral bodies 1422-1424.

The illustrated embodiment is merely an example and it can be imaginedthat the plate spans a plurality of vertebral bodies having a pluralityof regions that are aligned with the interbody spaces between vertebralbodies. These regions may include one or more bone growth promotingagents. Additionally, there may be a plurality of regions that do notcontain bone growth promoting agents.

In some cases, following surgical correction along the lamina region ofthe vertebral body, it may be necessary to increase the diameter of thespinal canal. Preferably, a spinal fixation system may includeprovisions that may be used to increase the diameter of a spinal canalas well as to promote new bone growth. This widened canal configurationmay allow for an increase in new bone growth over the originally narrowcanal.

FIG. 68 is an exploded view of spinal fixation system 1375. In thisembodiment, spinal fixation system 1375 includes plate 1380. Plate 1380may be any type of plate, including plates similar to those previouslydiscussed. In general, plate 1380 may have any shape and/or size.Preferably plate 1380 is shaped to fit on the side of spinal canal 1376.

Spinal fixation system 1375 further includes screw set 1381. The screwscomprising screw set 1381 may be any type of screw configured to insertinto bone. Generally, the number of screws in screw set 1381 may vary.In a preferred embodiment, screw set 1381 includes two screws.

Preferably, plate 1380 and screw set 1381 may be associated withvertebral lamina 1384. In this embodiment, vertebral lamina 1384 hasbeen split to increase the diameter of spinal canal 1376. Preferably,plate 1380 is oriented in a manner so that it attaches to first end 1378and second end 1379 of vertebral lamina 1384.

Preferably, spinal fixation system 1375 includes provisions forpromoting bone growth on vertebral lamina 1384. In a preferredembodiment, one or more bone growth promoting agents may be associatedwith plate 1380. Generally, one or more bone growth promoting agents maybe selectively applied to various regions of plate 1380. In thisembodiment, bone growth promoting agent 1392 may be selectively appliedto plate 1380 at first region 1438 and second region 1439, associatedwith screw set 1381. Additionally, in an alternative embodiment, one ormore bone growth promoting agents may be associated with screw set 1381.In another embodiment, the bone growth promoting agent is applied to theentire outer surface of plate 1380.

Preferably, the regions including bone growth promoting agents includeprovisions for new bone fusion at vertebral lamina 1384 and plate 1380.As seen in FIG. 69, new bone growth 1401 can be observed on plate 1380.With this configuration, new bone growth 1401 on plate 1380 provides forfusion between first end 1378 and second end 1379 of vertebral lamina1384. This preferably allows spinal canal 1376 to heal with a wideneddiameter, allowing for increased space of spinal canal 1376 whilepreserving spinal stability. Additionally, this preferred arrangementcreates a rebar effect, reinforcing the strength of the connectionbetween vertebral lamina 1384 and the vertebrae. This arrangement alsohelps to incorporate plate 1380 and screws comprising screw set 1381into the bone or bones. This design is advantageous over previoustechnologies because its allows for the incorporation of plates orscrews into the bone to augment fusion or healing, whereas previoustechnologies only allow for fixation of the bone members.

In some cases, a surgeon may need to apply one or more plates to thelateral portion of one or more vertebral bodies. This may be done in asimilar manner to the use of plates on the anterior side of a set ofvertebrae. Preferably, as with previous embodiments, the plates includeprovisions for promoting new bone growth or bony fusion at selectedregions of the vertebrae.

Referring to FIGS. 70-71, in some embodiments, first plate 502 may bedisposed along first lateral portion 501 of first vertebral body 504 andfirst lateral portion 503 of second vertebral body 506. Likewise, secondplate 550 may be disposed along second lateral portion 551 of firstvertebral body 504 and second lateral portion 552 of second vertebralbody 506. In the current embodiment, first vertebral body 504 may be acervical, thoracic or lumbar vertebral body. Likewise, second vertebralbody 506 may be a cervical, thoracic, lumbar or sacral vertebral body.

In some embodiments, first plate 502 is attached to first lateralportion 501 of first vertebral body 504 by first screw 511 and to firstlateral portion 503 of second vertebral body 506 by second screw 512.Also, second plate 550 may be attached to second lateral portion 551 offirst vertebral body 504 by third screw 513 and to second lateralportion 552 of second vertebral body 506 by fourth screw 514.Preferably, plates 502 and 550 each span space 520 that is disposedbetween first vertebral body 504 and second vertebral body 506. In somecases, space 520 may be filled in with bone or another substitute. Withthis configuration plates 502 and 550 may serve to hold first vertebralbody 504 and second vertebral body 506 together, as well as help to keepany bone or other material in place within space 520.

Referring to FIG. 71, in a preferred embodiment, a bone growth promotingagent may be selectively applied to plates 502 and 550. In thisembodiment, first side 530 of first plate 502 may include bone growthpromoting agent 540. Likewise, first side 531 of second plate 550 mayinclude bone growth promoting agent 540. Bone growth promoting agent 540may be selectively applied to sides 530 and 531 in any manner, includingthe various patterns previously discussed. Using this arrangement, bonegrowth promoting agent 540 may help plates 502 and 550 fuse to vertebralbodies 504 and 506. Furthermore, new bone growth may be promoted betweenvertebral bodies 504 and 506 using this configuration.

This preferred arrangement creates a rebar effect, reinforcing thestrength of the connection between adjacent vertebrae. This arrangementalso helps to incorporate plates 502 and 550 into the bone or bones.This design is advantageous over previous technologies that only allowfor fixation of adjacent vertebrae using one or more plates, but not theincorporation of the plates into the bone to augment fusion or healing.

In some embodiments, two adjacent vertebrae may be fused together usinga single screw. In some cases, a surgeon may need to fuse the sacralvertebral body, or the sacrum, to the L5 vertebral body. This may beachieved, for example, by inserting a single screw through a portion ofthe L5 vertebral body and into a portion of the sacrum. Preferably, thisscrew may include a bone growth promoting agent to facilitate bonefusion between the L5 vertebral body and the sacrum. Additionally, insome cases, a single screw with a bone growth promoting agent may alsobe used to fuse two lumbar vertebrae together.

FIG. 72 is an isometric view of a preferred embodiment of first spinalscrew 600 and second spinal screw 683. Spinal screws 600 and 683 may beany type of screw configured to insert into bone. In particular, aspreviously discussed, spinal screws 600 and 683 could be solid, hollowand/or cannulated. Spinal screws 600 and 683 may also include both macroand/or micro holes.

First spinal screw 600 is preferably associated with sacrum 602 andfirst vertebral body 604. In this preferred embodiment, first vertebralbody 604 is the L5 vertebral body of the lumbar region of the spine. Insome embodiments, first spinal screw 600 is inserted through facet joint610 of first vertebral body 604 into pedicle 612 of sacrum 602. Withthis configuration, vertebral body 604 may be fastened into place withrespect to sacrum 602.

Additionally, second spinal screw 683 is preferably associated withfirst vertebral body 604 and second vertebral body 684. In thispreferred embodiment, second vertebral body 684 may be the L4 vertebralbody of the lumbar region of the spine. In some embodiments, secondspinal screw 683 is inserted through facet joint 681 of second vertebralbody 684 into pedicle 682 of first vertebral body 604. With thisconfiguration, vertebral bodies 604 and 684 may be fastened together.

Preferably, spinal screws 600 and 683 include provisions for promotingbone growth. In some embodiments, spinal screws 600 and 683 may includeselectively applied bone growth promoting agent 620. Bone growthpromoting agent 620 may be any type of bone growth promoting agent. Inother embodiments, spinal screws 600 and 683 may include multiple bonegrowth promoting agents. Bone growth promoting agent 620 may beselectively applied to any portions of screws 600 and 683, including thevarious portions of screws previously discussed with respect to screwsin earlier embodiments.

Preferably, as seen in FIG. 73, new bone growth 650 may occur acrossfirst spinal screw 600 due to the presence of bone growth promotingagent 620. This preferred arrangement preferably creates a rebar effect,reinforcing the strength of the connection between sacrum 602 andvertebral body 604. Similarly, new bone growth 686 may occur acrosssecond screw 683 due to the presence of bone growth promoting agent 620.This preferred arrangement may also create a rebar effect, reinforcingthe strength of the connection between vertebral bodies 604 and 684.This arrangement also helps to incorporate screws 600 and 683 into thebone or bones. This design is advantageous over previous technologiesbecause it allows for the incorporation of the screw into the bone toaugment fusion or healing, whereas previous technologies only allow forfixation of the spine.

In the current embodiment, second screw 683 is associated with vertebralbodies 604 and 684. However, in other embodiments, second screw 683could be associated with other vertebral bodies as well. Generally, theconfiguration described here for fusing vertebral bodies 604 and 684using second screw 683 and a selectively applied bone growth promotingagent could be used with any adjacent vertebrae in the cervical, lumbar,or thoracic areas of the spine. In some cases, more than two vertebraecould be fused using this method.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

1. A spinal fixation system, comprising: a screw configured forimplantation into at least one vertebral body; the screw including ascrew body; a rod that is coupled to the screw using a coupling device;wherein the rod includes a first portion within the coupling device anda second exposed portion outside the coupling device, and wherein thesecond exposed portion of the rod includes a first region and a secondregion; wherein the first region of the second exposed portion of therod is a first radial section of the rod and wherein the second regionof the second exposed portion of the rod is a second remaining radialsection of the rod; wherein the first radial section is limited to aportion of the rod that is visible when viewing the rod from a directionin which the screw extends from the rod; wherein the first region of therod has bone growth promoting agent and the second region remainsexposed without bone growth promoting agent; wherein the first regionincludes a first area having a bone growth promoting agent selectivelyapplied in a first pattern and a second area having a bone growthpromoting agent selectively applied in a second pattern; and wherein thefirst pattern is different from the second pattern.
 2. The spinalfixation system according to claim 1, wherein the rod is associated withtwo or more screws, each screw including a screw body with a bone growthpromoting agent selectively applied to the screw body.
 3. The spinalfixation system according to claim 1, wherein the bone growth promotingagent is applied to the screw and the coupling device, and wherein thebone growth promoting agent extends from the first region of the rod,through the coupling device, and to the screw.
 4. The spinal fixationsystem according to claim 1, wherein the first pattern comprises astriped pattern and the second pattern comprises a spotted pattern. 5.The spinal fixation system according to claim 1, wherein the rod isassociated with multiple hooks and multiple connecting devices forfixing the hooks to the rod, and wherein the multiple hooks include aselectively applied bone growth promoting agent.
 6. The bone fixationsystem according to claim 1, wherein the first pattern comprises astriped pattern and the second pattern comprises a striped patterndifferent from the striped pattern of the first pattern.
 7. The spinalfixation system according to claim 1, wherein the bone growth promotingagent is applied to the first area in a spotted pattern comprising aplurality of spaced apart spots.
 8. The spinal fixation system accordingto claim 7, wherein the spaced apart spots vary in shape.
 9. The spinalfixation system according to claim 1, wherein the first radial sectionand the second radial section are approximately equal.
 10. The spinalfixation system according to claim 1, wherein when the spinal fixationsystem is implanted in the at least one vertebral body, the first regionof the second exposed portion of the rod is associated with an anteriorside of the at least one vertebral body and the second region of thesecond exposed portion of the rod is associated with a posterior side ofthe at least one vertebral body.
 11. The spinal fixation systemaccording to claim 1, wherein the first area and the second area arelongitudinally spaced apart.
 12. The spinal fixation system according toclaim 1, wherein the bone growth promoting agent is applied to the firstarea in a geometric pattern comprising a checkerboard.
 13. The spinalfixation system according to claim 1, wherein the bone growth promotingagent of the first area is different from the bone growth promotingagent of the second area.
 14. A spinal fixation system, comprising: afirst screw configured for implantation into a first vertebral body anda second screw configured for implantation into a second vertebral body;the first screw and the second screw each including a first screw bodyand a second screw body; a rod that is coupled to the first screw andthe second screw using a first coupling device and a second couplingdevice, wherein the rod includes a first portion within the firstcoupling device, a second portion within the second coupling device, anda third exposed portion between the first and second coupling devices,and wherein the third exposed portion of the rod includes a first regionand a second region; wherein a bone growth promoting agent is applied tothe first and second screw bodies, wherein the first region of the thirdexposed portion of the rod is a first radial section of the rod andwherein the second region of the third exposed portion of the rod is asecond remaining radial section of the rod; wherein the first radialsection is limited to a portion of the rod that is visible when viewingthe rod from a direction in which the screw extends from the rod;wherein the first region of the rod has bone growth promoting agent andthe second region remains exposed without bone growth promoting agent;wherein the first region includes a first area having a bone growthpromoting agent selectively applied in a first pattern and a second areahaving a bone growth promoting agent selectively applied in a secondpattern; and wherein the first pattern is different from the secondpattern.
 15. The spinal fixation system according to claim 14, whereinthe first screw is associated with a first screw set that is configuredfor implantation into the second vertebral body.
 16. The spinal fixationsystem according to claim 15, wherein the screws comprising the firstscrew set include screw bodies with a selectively applied bone growthpromoting agent.
 17. The spinal fixation system according to claim 14,wherein the second screw is associated with a second screw set that isconfigured for implantation into the first vertebral body.
 18. Thespinal fixation system according to claim 17, wherein the screwscomprising the second screw set include screw bodies with a selectivelyapplied bone growth promoting agent.
 19. The spinal fixation systemaccording to claim 14, wherein the bone growth promoting agent isapplied to the first screw, the second screw, the first coupling device,and the second coupling device, and wherein the bone growth promotingagent extends from the first screw, through the first coupling device,through the first region of the rod, through the second coupling device,and to the second screw.
 20. The spinal fixation system according toclaim 14, wherein the first coupling device and the second couplingdevice include a bone growth promoting agent.
 21. The spinal fixationsystem according to claim 14, wherein the first pattern comprises astriped pattern and the second pattern comprises a spotted pattern. 22.The spinal fixation system according to claim 14, wherein the firstpattern comprises a striped pattern and the second pattern comprises astriped pattern different from the striped pattern of the first pattern.23. The spinal fixation system according to claim 14, wherein the firstradial section and the second radial section are approximately equal.24. The spinal fixation system according to claim 14, wherein when thespinal fixation system is implanted in the first vertebral body, thefirst region of the third exposed portion of the rod is associated withan anterior side of the first vertebral body and the second region ofthe third exposed portion of the rod is associated with a posterior sideof the first vertebral body.
 25. The spinal fixation system according toclaim 14, wherein the first area and the second area are longitudinallyspaced apart.
 26. The spinal fixation system according to claim 14,wherein the bone growth promoting agent is applied to the first area ina spotted pattern comprising a plurality of spaced apart spots.
 27. Thespinal fixation system according to claim 26, wherein the spaced apartspots vary in shape.
 28. The spinal fixation system according to claim14, wherein the bone growth promoting agent is applied to the first areain a geometric pattern comprising a checkerboard.
 29. A spinal fixationsystem, comprising: a screw configured for implantation into at leastone vertebral body, the screw including a screw body; a rod; and acoupling device that couples the rod to the screw with the screwextending in a direction transverse to the rod, wherein the rod includesa first covered portion within the coupling device and a second exposedportion outside the coupling device, wherein the second exposed portionof the rod includes a first region and a second region, wherein thefirst region of the second exposed portion of the rod is a first radialsection of the rod and wherein the second region of the second exposedportion of the rod is a second remaining radial section of the rod;wherein the first radial section is limited to a portion of the rod thatis visible when viewing the rod from the transverse direction in whichthe screw extends from the rod; wherein the first region of the rod hasbone growth promoting agent and the second region remains exposedwithout bone growth promoting agent; wherein the first region includes afirst area having a bone growth promoting agent selectively applied in afirst pattern and a second area having a bone growth promoting agentselectively applied in a second pattern; and wherein the first patternis different from the second pattern.